You can purchase additional Sapphires at the Bank by selecting the "Bank" button in the top right-hand corner of the screen.
You can also get Sapphires by completing various actions within the game:
- Completing specific game tasks and quests.
- Logging into the game daily and collecting the Day 30, Day 60, and Day 90 rewards.
- Placing in one of the top positions of the Rankings.
- Completing Achievements.